Fix usermod validation portability

Use proper path analysis instead of bare text matching.

Co-authored-by: Claude <noreply@anthropic.com>

pio-scripts/validate_modules.py

@@ -49,25 +49,36 @@ def check_elf_modules(elf_path: Path, env, module_lib_builders) -> set[str]:
         secho(f"WARNING: nm failed ({e}); skipping per-module validation", fg="yellow", err=True)
         return {Path(b.build_dir).name for b in module_lib_builders}  # conservative pass
 
-    # Build a filtered set of lines that have a nonzero address.
+    # Collect source file Paths from placed symbols (nonzero address only).
     # nm --defined-only still includes debugging symbols (type 'N') such as the
     # per-CU markers GCC emits in .debug_info (e.g. "usermod_example_cpp_6734d48d").
     # These live at address 0x00000000 in their debug section — not in any load
     # segment — so filtering them out leaves only genuinely placed symbols.
-    placed_lines = [
-        line for line in nm_output.splitlines()
-        if (parts := line.split(None, 1)) and parts[0].lstrip('0')
-    ]
-    placed_output = "\n".join(placed_lines)
+    # nm -l appends a tab-separated "file:lineno" location to each symbol line.
+    placed_paths: set[Path] = set()
+    for line in nm_output.splitlines():
+        parts = line.split(None, 1)
+        if not (parts and parts[0].lstrip('0')):
+            continue  # zero address — skip debug-section marker
+        if '\t' in line:
+            loc = line.rsplit('\t', 1)[1]
+            # Strip trailing :lineno  (e.g. "/path/to/foo.cpp:42" → "/path/to/foo.cpp")
+            file_part = loc.rsplit(':', 1)[0]
+            placed_paths.add(Path(file_part))
 
     found = set()
     for builder in module_lib_builders:
         # builder.src_dir is the library source directory (used by is_wled_module() too)
-        src_dir = str(builder.src_dir).rstrip("/\\")
-        # Guard against prefix collisions (e.g. /path/to/mod vs /path/to/mod-extra)
-        # by requiring a path separator immediately after the directory name.
-        if re.search(re.escape(src_dir) + r'[/\\]', placed_output):
-            found.add(Path(builder.build_dir).name)
+        src_dir = Path(str(builder.src_dir))
+        # Path.is_relative_to() / relative_to() handles OS-specific separators
+        # correctly without any regex, avoiding Windows path escaping issues.
+        for p in placed_paths:
+            try:
+                p.relative_to(src_dir)
+                found.add(Path(builder.build_dir).name)
+                break
+            except ValueError:
+                pass
     return found